JPS5886451A - Concentration detector for developer - Google Patents

Abstract

PURPOSE:To detect the concn. of a developer with high accuracy by connecting capacitive load to one of a pair of coils wound on a vessel which stores the developer and comparing the output currents of both coils. CONSTITUTION:A reactor 1 is constituted of a square cylinder 2 formed of an insulator such as a resin material, coils 3, 4 wound respectively to the cylinder 2, and an iron core 5 which serves also as a magnetic path and a shield and is stuck on the side surface of the cylinder 2 so as to ride across the coils 3, 4. When the amt. of the toner in the cylinder 2 decreases, the amt. of the carrier, for example, the amt. of iron powder, increases relatively; therefore, the magnetic resistance of the magnetic path by the iron powder decreases and the number of magnetic lines of force increases with respect to the magnetic fields generated by the currents flowing in the coils 3, 4. As a result, the reactances of the coils 3, 4 increase and the inflow currents decrease. Conversely, when the amt. of the toner increases, the inflow currents of the coils 3, 4 increase. Thus, phase differences are given to the currents flowing into the coils 3, 4 by means of a capacitor 11 and the current values flowing in both coils are compared, whereby the concn. of the developer is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a developer concentration detection device for an electronic copying machine.

Electronic II! The developer used in the developer is made up of two components: a carrier such as iron powder or 7-ethite, and a toner, and the toner concentration in this developer must always be maintained at an optimum level.

This invention was made under the circumstances mentioned above, and the u
The object of the present invention is to provide a developer concentration detection device that has a simple configuration, can perform highly accurate detection, and maintains good controllability and stability.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, numeral 1 is a glue actor for detecting the concentration of the developer, and this reactor l consists of a rectangular tube 2 formed of an insulator such as W& material, and windings each wrapped around the rectangular tube 2. installed coil 3.

4, the magnetic path and the shield are not attached, and the above-mentioned coils 3 and 4
The iron core 5 is fixed to the side of the square tube 2 so as to straddle the
It consists of. Furthermore, a bottom II 16 that rotates around the shaft 7 is straddled on the bottom side of the rectangular tube 2. When measuring the concentration of the developer, the bottom cover 6 is closed and the developer 8
is sufficiently filled in the rectangular tube 2, and changes in the current flowing through the coil 3.4 are detected by the circuit shown in Figure 3, which will be described later. After the density measurement, the bottom cover 6 is opened and closed every time the photosensitive drum rotates, the developer 8 is discharged, and new developer is replenished.

The mechanism of the reactor 1 described above is implemented using the following basic ring. That is, when the amount of toner in the rectangular tube 2 decreases, the amount of carrier, for example, the amount of iron powder, increases relatively, so that the magnetic field generated by the current flowing through the coil 3.4 is affected by the magnetic path caused by the iron powder. The resistance decreases and the number of magnetic field lines increases,
Therefore, the reactance of the coil 3.4 increases and the inflow current decreases. On the other hand, as the amount of toner increases, the amount of iron powder is relatively destroyed, so the magnetic resistance increases, the lines of magnetic force also decrease, the reactance of the coil 3.4 decreases, and the inflow current increases.

The characteristic curve diagram in Fig. 2 shows the above-mentioned principle, and shows the changes in coil 3°4 glue actance X (Ω) and current 1 (, -A) with respect to changes in toner concentration (%), respectively.
It is indicated by song II9 or song @10. Note that the applied voltage is constant.

Next, a circuit that detects the concentration of the developer by capturing the above-mentioned current change using the third WJ will be described. Input terminal 23.2
An alternating current voltage is supplied between the four terminals. Further, one end of each of the capacitor 11 and the coil 3.4 is connected to the input terminal 23, and the capacitor 11. Each other end outside the coil is connected to one AC terminal of the rectifier 12, and the other end of the coil 4 is connected to one AC terminal of the rectifier 15. The other AC terminals of the rectifiers 12, 15 are then connected together to the input terminal 24.

There is a capacitor between the DC terminals of the rectifier 12? 13 and a volume 14 are connected in parallel, and a capacitor 16 and a volume 17 are connected in parallel between the DC terminals of the rectifier 15. The negative pole side is grounded to the saddle.

The sliding terminals 14 and 17 of the medium 14.1 are connected to the e input terminal and the ■ input terminal of the comparator 18, respectively. A DC voltage is supplied to the comparator 18 and other illustrated circuits through a terminal 25 (positive electrode) and a terminal 26 (negative electrode). A resistor 1G is connected between the output terminal of the comparator 18 and the input terminal 25, and the output terminal of the comparator 18 and the base terminal of the transistor 20 are connected.

The two vine terminals of the F-run raster 20 are grounded, and a solenoid 21 and a diode 22 are connected in parallel between the collector terminal and the input terminal 25.

Next, 4th to 6th meter! i! The operation will be explained with reference to ff. In the following explanation of the operation, both the internal resistance and mutual inductance of the coil 3.4 will be ignored. FIG. 4 shows the states of the shared voltages of the coil 4 and the volume A 17 based on a vector diagram assuming a series circuit of the volume 17 with the coil 4 and rectifier 15 in FIG. 3 removed.

First, if the inflow current when the developer has a predetermined concentration is 1, the current 1 is out of phase with the applied voltage because it is a 1IIIl load, and the voltage shared by the volume 17 that is in phase with the current 1 is VR17? -t'', and furthermore, the shared voltage of the coil 4 is the above-mentioned shared voltage yRBwtJ:ζ whose phase is advanced by 90 degrees and is VL.

Further, when the concentration of the developer is low, the current decreases to 1' for the reason mentioned above. Therefore 19 neem 1
The shared voltage of coil 7 also decreases to VRl,', and the shared voltage of coil 4 increases to v' by 4/.

As can be seen from the above, the voltage shared by the volume 17 decreases as the concentration of the developer decreases, and therefore the voltage shared by the volume 17 converted into DC via the rectifier 15 also has the same rate of change 4i.

FIG. 5 is a petacil diagram showing the state of voltage sharing when a series circuit of the volume 14 is assumed, excluding the coil 3, capacitor 11, and rectifier 12 in FIG.

Now, one condition is that the companion current I flowing into the coil 3
A case is set in which lead current 1 (l) flowing into the capacitor 11 is larger than L. Under this condition, when the concentration of the developer is a predetermined concentration, the voltage shared by the capacitor 11 and the coil 3 is set as va:ci. , this shared voltage vC
Current 1L for coil 3 and capacitor +11 for L, respectively.
Assuming that ito flows in, the two are in opposite phase, so
A current of the difference 10-11 flows through the clamp 14, and its shared voltage is indicated by VJ4.

When the developer concentration decreases under the above conditions, the current flowing into the coil 3 decreases to II/1, and therefore the above difference increases to 1 cm x XI. Therefore, the voltage shared by the volume 14 increases to "R14", and the voltage shared by the capacitor 11 and the coil 3 decreases to vOx!.

In this way, when the concentration of the developer decreases, the voltage shared by the volume 14 increases, and therefore the rate of change of the DC current through the rectifier 12 remains the same.

In the 61i, the above-mentioned shared voltage is changed to a direct current, and the change curve of the shared voltage VRy with respect to the developer concentration is changed to the curve 1[2γ
The change curve of shared voltage VP'q 4 is shown as 1s.
28.

Assume now that the density setting position is density position 29 where songs 927 and 28 intersect, and that the density has decreased to position 30. At this time, the potential of the e terminal becomes lower than that of the e terminal of the comparator 18 shown in FIG. Therefore, the transistor 20 is turned on, and the solenoid 21 is energized to drive the toner supply device (not shown), supplying toner into the developing device, and after stirring with the already existing developer, the developer is deposited in the corner 11t2. be arrested. This operation continues until the density returns to position 2 again. Immediately, the unbalanced voltage generated at the e terminal and the e terminal of the comparator 18 is an extraction signal based on the developer density aspect ratio. The above operation explanation describes the generation process of the envy signal when the density decreases from the set density, but when changing the set value of the density, adjust the volume 14 and the height 17 and change the intersection position 29 of the song 1127.28. can be moved to obtain the desired concentration.

When the frequency of the voltage applied to the connected terminals 23 and 24 is increased, the capacity of the reactor 1 and the capacitor +11 can be reduced in size, and even in this case, a sufficient extraction signal can be obtained. Furthermore, when viewed from the input terminal 23° 2411, the current flowing through the capacitor 11 and the current flowing through the coil 4 are in opposite phase to each other, so it is sufficient to supply the difference current. There are also effects such as the capacity can be made smaller.

As explained above, in this invention, a capacitive load is connected to one of a pair of fills wound around a container storing developer, and the concentration of the developer is detected by the ratio of the output currents of both coils. Because of this configuration, detection can be performed with high accuracy, controllability and stability are maintained well, and the configuration is simple and can be miniaturized.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the configuration of a glue actor 1 according to an embodiment of the present invention, and FIG.
Change in rearatance X (Ω) of 4-@* and electrode ihm)
A diagram showing the change in - [110, sWi is the circuit IIL
Figures 4 and 5 are vexile diagrams, respectively, and the figures show the shared voltage vFII for developer concentration. Change in -@2γ and change curve 28 in shared voltage VB14
FIG. l...-reactor, 2haa...square tube, 3.4
--- Coil, S --- Iron core, 6 --- Bottom cover, 11 --- Capacitor, IZa 1, 6 ---
・・・Rectifier, 14.17・・・Poly-凰-人,
18...Comparator, 20...Transistor, 21-...A-Relay. Fig. 1 Fig. 2 Hoyu - Fig. 3 Fig. 4 Fig. 5 Fig. 6 Hirot! L(?/,)

Claims (1)

[Claims] A cylindrical container that stores developer for an electronic value machine, a pair of fills wrapped around the container, and a coil connected to only one of the pair of coils to handle the inflow current. A developer concentration detection device comprising a capacitive load whose phase is advanced, and a comparison device which compares the output current of one of the fills and the output current of the other coil.